Work holder for lapping machines



March 11, 1958 R. o. SHURSON 1 2,826,009

WORK HOLDER F OR LAPPING MACHINES Filed D90. 10, 1954 3 Sheets-Sheet 1IN VEN TOR. YMQND 0. SHUR$ON R. o. SHURSON WORK HOLDER FOR LAPPINGMACHINES March 11, 1958 3 Sheets-Sheet 2 Filed Dec. 10. 1954 FIG-2INVENTOR.

R AYMOND O. SHURS ON March 11, 1958 R. o. SHURSON 2,8

'- WORK HOLDER FOR LAPPING MACHINES Filed Dec. 10, 1954 Y s Sheets-Sheet5 INVENTOR.

RAYMOND O. SHURSON w BY United States Patent WORK HOLDER FOR LAPPINGMACHINES Raymond 0. Shnrson, Chicago, Ill., assignor to Crane PackingCompany, Chicago, 111., a corporation of Illinols Application December10, 1954, Serial No. 474,546

7 Claims. (Cl. 51-129) The improved work holder comprising the presentinvention has been designed primarily for use in connection with thepositioning of articles on a lap plate, the platebeing formed with oneor more annular grooves in the upper surface thereof and the articlesbeing formed with shoulders thereon which are designed to beardownwardly on the land surfaces of the lap plate which exist on oppositesides of the various grooves. Certain articles, as for example valvedisks or plates, rotary seal seats, fuel pump parts and a wide varietyof other objects, are formed with an annular surface thereon which isaxially spaced from the opposite ends of the part thus defining ashoulder, the surface of which it is desired shall be lapped to asubstantially fiat condition.

As shown in the United States patent to Roshong, No. 2,597,382, datedMay 20, 1952, for Apparatus for Lapping Shoulders, it has been customaryto maintain such articles on the grooved lap surface with the shouldersundergoing lapping resting on the land areas on opposite sides of theintervening groove by means of a centering spindle which projects intoan opening provided in the article and which serves to hold the articleon the lap to prevent the same from riding with or revolving about thelap axis. Where the character of the work is such that it is relativelyheavy or where it possesses considerable height, it has been found thatthe restraining force acting on the article at a considerable distancefrom its region of support on the lap surface causes a tilting of thearticle and this tilting may result either in a gouging of the lapsurface or in the application of unequal pressure between the lapsurface and the various increments of the surface resting thereon andundergoing lapping. Furthermore, where the diameter of the annularsurface on the article undergoing lapping is relatively small and thewidth of the groove existing between the adjacent land areas on the lapis, as a consequence, relatively narrow, the friction differentialbetween the lap and surface on opposite sides of the groove cannot berelied upon to induce free rotation of the article supported on the lapinasmuch as the circumferential speed of the outermost land area is notappreciably greater than the circumferential speed of the innermost landarea and for this reason a more positive method of causing rotation ofthe article on the lap surface is required.

The present invention is designed to overcome the above notedlimitations that are attendant upon the use of apparatus such as hasbeen shown in the patent to Roshong as well as to provide a morepositive means for effecting induced rotation of an article resting onthe lap surface. Toward this end the invention contemplates theprovision of a work holding means which will effectively maintain anarticle of the character set forth above on a grooved lap surface withits annular shoulder resting upon the land areas of the lap while at thesame time holding the article against revolution about the axis of thelap while permitting a more effective frictional contact between thearticle and a surface of the lap plate Patented Mar. 11,1958? which issufiicient to provide the necessary induced rota tion for causing thearticle to rotate about its own axis.

The provision of an apparatus of the character briefly outlined abovebeing among the principal objects of the present invention, it is afurther object of the invention to provide a work holder of thischaracter which will accommodate the positioning of multiple objects ona multi-grooved lap plate, a single work holder serving to maintain twoor more of the objects in their respective radially displaced positions.

It is a still further object of the invention to provide a work holderof this sort which is readily adjustable to accommodate objects ofdifferent diameter as well as to accommodate varying spacing between theland areas on the lap plate which may be encountered. A similar andrelated object of the invention is to provide an adjustable work holderof this sort wherein adjustments may be made from time to time wherevernecessary without stopping the operation of the machine and Without thenecessity of unfastening or disassembling any of the machine parts.

Yet another object of the invention is to provide a work holder designedfor use in connection with grooved lap plates, particularly lap plateshaving multiple grooves therein which will permit the insertion of workinto the machine and the removal of work therefrom without stopping theoperation of the machine.

Still another object of the invention is to provide a work holder forlapping machines of this character which will not interfere with theoperation of the usual conditioning or wear rings employed formaintaining the lap plate fiat as to contour and which will permit thework to be lapped within the conditioning ring thus economizing inavailable lapping area and contributing toward maximum machine outputover any given period of time.

The provision of a work holder for lapping machines of the type setforth above which is extremely simple in its construction and whichtherefore may be manufactured at a low cost; one which is comprised of aminimum number of moving parts and which therefore is unlikely to getout of order; one which, when installed in the lapping machine, isreadily accessible at all times, even during machine operations, forpurposes of inspection or adjustment; one which is capable ofsubstitution when necessary without shutting down machine operation; andone which is otherwise well adapted to perform the services required ofit, are further desirable features that have been borne in mind in theproduction and development of the present invention.

Other objects and advantages of the invention, not at this timeenumerated, will become more readily apparent as the nature of theinvention is better understood.

In the accompanying three sheets of drawings forming a part of thisspecification, a preferred embodiment of the invention has beenillustrated.

In these drawings:

Figql is a fragmentary perspective view of a lapping machine having amulti-grooved lap plate and showing the improved work holder comprisingthe present invention operatively associated therewith. In this view a.pair of articles of the type capable of being lapped by the presentmachine is shown resting upon the machine table surface.

Fig. 2 is a sectional view taken substantially along the plane indicatedby the line 22 of Fig. 1.

Fig. 3 is a sectional view taken substantially along the line 3-3 ofFig. 2 in the direction indicated by. the arrows.

Fig. 4 is an enlarged detail fragmentary perspective view, partly insection, taken in the vicinity of the lap, surface and illustrating themanner in which the present work holder operates to maintain the workoperatively positioned on the lap surface, and

Fig. 5 is a sectional view taken substantially along the planeindicated.by .theline 55 of Fig.v 4.

-Referring IZOW'tO the drawings in detail and in particular to Fig. 1,there is shown a lapping.. rnachine of the general type-shown and.described in the United States reissue patentto Bullard, Re.23,937,.dated February 8,. 1955, for Lapping Machine.

Briefly, this machine involves in its general organization a stationaryframework of table-like design and including a table top 12 havingapron-like sides 14. Projecting upwardly through a circular opening 16in the table portion 12 is a rotatable lap plate 18 preferably formedof. cast iron or other suitable material and having an annular abradingsurface 20 provided with a series of radially spaced circumferentiallyextending grooves 22 formed therein which divide the surface 20 intoaseries of relatively narrow annular land areas 24. The upper lappingsurface 20 of the lap plate 18 is adapted to receive thereon a pluralityof wear rings26, commonly known as conditioning rings. These rings arepreferably formed of the same material as the material of the lap plate,i. e. cast iron, and the rings are of such diameter that they may bepositioned on the lap area so as to overlap slightly both the inner andouter peripheries 28 and 30 respectively as clearly shown in Figs. 2 and3. .The conditioning rings 26 are adapted to rest frictionally on thesurface of the lap annulus, bridging the various grooves 22 and landareas 24 and means are provided for preventing them from riding with thelap, so to speak, or in other-Words, for holding them against revolutionabout the axis of the lap so that each ring is held permanently withinits own sector of the lap annulus. In order to thus support the ringsagainst revolution about the lap axis, each ring has secured thereto aninverted U-shaped yoke 32 which may be secured to the upper rim of thewear ring by anchoring studs 34 and which assumes a diametric positionwith respect to the wear ring. Each yoke is formed with a central hubportion 36 which loosely surrounds a vertically extending spindle 38which interlocks by a pilot connection at its upper end as at 40 with aradially adjustable spindle 42 which also is capable of angularadjustmentand which is suitably carried in the machine framework in amanner that will be made clear presently. The degree of pressure exertedby each conditioning ring on the lap annulus may be regulated byadjusting the compressional force exerted by a coil spring 43 on theyoke32 by means of avertical-ly adjustable collar 45 which surrounds thespindle 38vand having a set screw 47 associated therewith. A small orlimited amount of universal movement is permitted between eachconditioning ring. 26 and the vertical axis of its respective spindle-38so that the, ring will at all times rest squarely upon the lap annulusin face-to-face contact with the land areas 24 thereof. A series ofspaced angularly disposed slots 49 are formed in the lower regions ofeach ring 26 and are effective to more efficiently distribute thelapping compound which is supplied to the lap surface as will bedescribed subsequently.

Spaced above the general plane of the lap annulus and overlying thelatter is a horizontally disposed spider 44 (Fig. 1) including a shankportion 46 and three spider arms 48. The spider 44 is supported abovethe lap plate by means of a depending attachment flange shown in dottedlines in Fig. 1 at 50 and which may be selectively secured in variouspositions of vertical adjustment to. a. housing 52 mounted on the tableportion l 2;..and:which-serves to: support certain electric controlinstrumentalities associated with the machine. The free end of eachspider arm 48 is formed with an enlarged boss-54 (see alsoFig. 2) inwhich there is rotatably di po ed acyl iniri a v a justing b ock 56 a na n r e head portion 58. The adjusting block is formed with aneccentrically displaced vertical bore 60 therethrough in which thevertically disposed spindle 42 is adapted to be clamped in any desiredposition of adjustment by means of a set screw 62. The adjusting block56 is capable of being clamped in any selected angular position ofadjustment by means of a clamping screw 64. An indicator or pointer. 66cooperates with a suitable scale 68 provided on the head portion 58 sothat the angular position of the adjusting member. 56 and the consequentextent of radial displacement of the spindle 42 with respect to thecentral axis of the lap surface may be readily ascertained.

The mechanism just described forshifting the radial position of theconditioning'rings 26 allows the lap surface to be automatically dressedduring lapping operations under controlled conditions whereby the lapannulus may be. brought to a fiat condition when the. same .is;found tohave assumed either. a convex or a concave shape. The extent of overhangof the wear ringson .eitherthe outsidev or inside edges 28, 30 is thecontrol factor for effecting dressing operations. If the overhang isgreater at the outside than at the inside, the unbalanced force :Willtend to wear the lap surface convex. Conversely,'if the amount ofoverhang at the inside is greater, the lap will tend to become concave.In the .former instance, .it will benecessary to. adjust the member 56so that the spindle'42 will be moved radially inwardly and in. thelatter .instance'it is necessary to make the adjustment so that thespindle will be moved radially outwardly a predetermined distance.

It is essential to the operation of a machine of this character that thesurface of the lap plate be supplied with a lapping compound consistingof a gritty fluid including a suitable vehicle in which particles ofgrit or abrasive aremaintainecl in suspension. Accordingly, a tank orreceptacle 70 (Fig. 1) is supported above the table portion on thehousing 52 and has disposed therein an agitator mechanism (not shown),the central shaft or spindle 72 of which projects upwardly above thetank and is driven through a suitable gear reduction mechanism 74 froman electric motor M suitably supported on a platform 76 mounted on thetank 70. The liquid contained within thestank 70 and in which theparticles of grit are suspended, is adapted to flow outwardly through adischarge orifice 78, the opening and closing movements of which areconducted bymeans of a solenoid actuated valve 80. From the orifice thisgrit laden fluid may flow along a flexible wire 82 and be applied to theside of one of the conditioning rings 26 against which it bears so thatfluid will be conducted to the ring and then distributed over thesurface of the lap annulus 20 including the land areas 24 as the latterpass beneath the wear ring 26. The housing 52 serves tosupport theagitator tank 70 as well as the various electrical control components ofthe machine. The lap. plate 18 is adapted to be driven from an electricmotor (not shown) suitably supported beneath the table top 12. and thismotor togetherwith the motor M as well as thesolenoid valve and certaintiming mechanism designatedagenerally at 84 all operate under thecontrol of a series ofswitches-86 mounted on the side of the housing 52.

The arrangement of parts thus far described is more orlessconventionaland no claim is made herein to any novelty associated with the same, thenovelty of the present invention residing rather in theconstruction,combination, and arrangement of parts about to be described.

'Referring now to Fig. l, twoarticles, one designated at; A and theother designated at A, are shown resting on the surface of the'tableportion. 12. The article A, illustrated herein purely for exemplaryvpu1poses,.is in the form of valve parts designed for use in connectionwith air craft fuel pumps. Each partA includes a central stem orv shaft96) carrying atits oppositeendsa pair of gears 92 and 94rrespectively.:At a point; intermediate. the twogears.

. is a disk element 96 having an annular surface 98 thereon which it isdesired shall be lapped to a substantially fiat condition. The article.A is in the form of a cylindrical object having a body portion a and astem portion 11.

According to the present invention it is contemplated that more than onepart will be lapped simultaneously by the machine and that the variousparts undergoing lapping may be identical or of different design.Accordingly, for illustrative purposes, each conditioning ring is shownas enclosing one of the parts A and one of the parts A. Each part A hasits lower stem portion 90 and gear 94 disposed within one of the grooves22 and with the surface 98 on the disk 96 loosely resting on a pair ofadjacent land areas 24. In the present instance, as shown in Fig. 4-,the

two parts A and A overlie the grooves 22 which are not adjacent eachother but which are disposed on the opposite sides of an intermediategroove. In this manner the disk 96 of the part A has its surface 98resting on two different land areas 24 from the land areas on which thebody portion a of the article A rests and there is no chance forinterference between the movements of the two parts A and A. In order toincrease the effective lapping pressure between the surfaces 98 of thearticles A and the lap surfaces 24, a cylindrical weight 99 ispositioned over the upper gear 92 and this weight exerts a downwardgravitational influence on the article. The weight 99 is formed with asocket 101 therein, the wall of which is formed with an annularsemi-circular groove 103 in which there is disposed a resilient O ring105, the ring serving to frictionally grip the teeth on the gear 92 andmaintain the weight 99 centered over the article.

In order to restrain the articles A and A against revolution about theaxis of the lap the improved work holder of the present invention hasbeen provided and is designated in its entirety at 100. The work holderincludes a portion of the adjustable mechanism shown in the upperportion of Fig. 2 as well as the spindles 38 and 42 and the additionalmechanism carried at the ,lower end of the spindle 38. This lattermechanism, briefly, includes a pair of antifriction members or rollers102 and 104 respectively capable of individual adjustment with respectto the spindle 38 and each of which is adapted to be suspended from thespindle 38 at a predetermined position positioned directly in the pathof movement of one of the articles A or A resting frictionally on thelap so that the roller will bear against the cylindrical side of theweight 99 carried by the article and so that the article will berestrained in its tendency to ride with the lap. In order to thussupport the rollers 102 and 104, the lower end of the spindle 38 isprovided with a relatively deep socket 106 in which there is slidablyand turnably mounted an elongated clamping rod 108 capable of beingmoved from the retracted position shown in Fig. 2 in full lines to theextended dotted line position. The lower end of the rod 108 threadedlyreceives a clamping screw 110 having an enlarged head 112 and a washer114 thereon. Interposed between the washer 114 and the underneathclamping surface 116 of the clamping rod 108 are the horizontal armportions 120 of a pair of adjustable roller supports 122 and 124respectively carrying the rollers 102 and 104. The arm portions 120 ofthe two supports are provided with elongated narrow slots 126 throughwhich the clamping stud 110 passes. The supports 122 and 124 are similarin their construction and each carries at its free outer end a fasteningscrew 128 on which screw the respective rollers 102 and 104 arerotatably mounted. The clamping member 122 is provided with a laterallyoffset portion 130 so that the two studs 128 and their respectiverollers may be positioned at substantially the same elevation withrespect to the lapping surface of the lap plate 18.

The side wall of the socket 106 is provided with an elongated verticalslot 132 therein and an operating handle orpin 134'projects through theslot 132 and into the rod 103 and is capable of being latched against ashoulder 136 on the" side wall of the slot 132 so as to hold the rod 108in its elevated retracted position wherein the lower end of the rod isdrawn within the confines of the socket 106 and the two arms of theclamping members 122 and 124 are firmly clamped against each other withthe upper surface of the overlying arm being clamped against the lowerend of the spindle 38. With the parts in this position, the two arms 122and 124 are securely held against radial or angular shifting movementand the rollers 102 and 104 respectively carried thereby are anchored inrelative fixed positions. When it is desired to adjust the position ofone or both of the two rollers, it is merely necessary to move thehandle 134 from its latched position on the shoulder 136 so that theclamping rod 108 may be moved downwardly in the socket 106 to releasethe arms 120, after which the positions of the rollers 102 and 104 maybe manually adjusted and thereafter the clamping mechanism againtightened in the manner previously described so that these rollers willremain locked in their adjusted positions. If desired, one or both ofthe opposed overlying surfaces on the arms 120 may be knurled orotherwise roughened to afiord good frictional characteristics betweenthese two parts and prevent slippage of one upon the other.

Referring now to Fig. 2, it will be seen that the upper end of each ofthe spindles 42 carries a knurled adjusting knob 140 by means of whichthe angular position of the rod 42 and consequently of the rod 38 androller supporting arms 122 and 124 respectively may be adjusted to varythe effective radial distance between the two rollers 102 and 104. Incertain instances, it may be found desirable to utilize adjacent grooves22 in the lap plate so that two articles undergoing lapping will shareone of the common land surfaces 24 with one article being positionedcircumferentially in advance of the other article. This has the efiectof reducing the effective radial extent between the two articles and toaccommodate such an arrangement the spindle 42 may be adjusted so thatthe two arms 122 and 124 maintain their respective rollers in positionswhich have an appreciable circumferential increment of displacement aswell as the necessary radial increment of displacement. As a matter offact, a wide diversity in the relative displacement as well as in theactual longitudinal and circumferential displacement of the rollersrelative to the lap axis may be eifected with the possible range ofadjustment of the two arms 122 and 124.

In the application of the work pieces or articles to the lap, theadjusting mechanism just described will be locked in an adjustedposition whereby one of the rollers 102 or 104 as the case may be ispositioned in the normal path of movement of an article disposed in oneof the grooves 22. The roller will be positioned slightly inwardly oroutwardly from the circular centerline of the article with respect tothe lap axis so that the article will have an unstable degree ofequilibrium with respect to the roller or in other words so that thearticle will be unbalanced on the roller and tend to ride on the lap insuch a manner as to pass around the roller either by being thrownradially inwardly or radially outwardly on the lap surface. If thetendency is for the article to move radially inwardly, it will beprevented from doing so by virtue of the fact that the depending portionof the article, in the present instance the lower gear 94 thereof, willbe forced against the inner vertical cylindrical wall 142 of the groove22. The article will then become lodged in a fixed position so that theresultant vectorial force exerted.

upon the article due to its frictional contact with the two land areas24 on opposite sides of the groove, is directed between the roller andthe restraining wall 142 and the article is thus prevented fromcontinuing in a circularpath around the axis of the lap. With thearticle thus.

restrained, the frictional contact of the depending gear 94 with thewall 142 will impart a counter clockwise.

rolling movement of the article A about a fixed vertical central axis sothat all increments of surfacearea on the surface '98 undergoinglapping, will -be-repeatedly moved intocontact with thetwo'land'areas'24.

' lnFigs; 4 and 5 the roller 102 isshown as being posiwise direction.The roller 104, however, is positioned slightly inwardly of the circularcircumferential axis of the other article undergoing l appi ng and 'insuch an instance there will be a tendency for -the-artic1e;to shiftradially outwardly on the lap so that the gearfl-t-thereof engages theouter wall 144 of the; groove 22. With the roller 104 thus positioned,an induced rotation will be set up in the article which isin a clockwisedirection as viewed in Fig. 4.

Whether the rollers 102 and 104 be positioned so that the article iscaused to bear againstone SidQ'Of the groove 22 or against the otherside of the grooye-is m'erely a matter of choice and the extent ornatureof the lapping operation will, in either instance, remainsubstantially the same. Theoretically, it would appear thatwhere-thearticle bears against the wall 144 and is thus caused torotate in acounter clockwise direction as viewed-dn' Fig. 4, a

slightly faster abrading action would be attained because of the factthat increments of the surface 98 on -the disk 96 undergoing lappingwill have a higher speed of relative motion with respect to theoutermost of the two land areas'than when the article is being rotatedinthe opposite direction. However, since these surface incrementsreverse their direction of movement relative to the moving surface ofthe lap once during each rotation of the article, and since thedifference in peripheral speedbetween increments of surface or onadjacent land areas 22 is very small indeed, the net overall effectafforded by positioning the roller in one or the other of the twodescribed operative positions will be negligible. Moreover, sincetheweight of the condition-ring 26 far exceeds the weight of thearticlesundergoing lapping, the effect of any wear that may take place on thelap plate by virtue of its frictional contact with the articles will beefiaced by the abrading action of the conditioning ring.

In Fig. 1, one of the three conditioning rings-26 is shown as receivingtherein for lapping purposes a pair of articles A including itscylindrical body portion a andits projecting stern portion b, the bodyportion providingfiun annular shoulder c which it is desired shall belapped to a flat condition. The article A"- possesses sufiicient'weightthat the-necessary degree of lapping pressure will be attained againstthe *land surfaces 24 and, since the body a is-cylindrical, there is nonecessity foremploying weights such as are shown at 99 in connectionwith-thegear parts. The articles A areplaced on the lap surface with 1 estems b thereof projecting into the grooves 22 solthat they may'bearagainst either the inner orouter side walls of the grooves to impartrotational movementgto the articles about their vertical axes. The othervisible conditioning ring is shown as receiving therein one of thearticles A and one of the articles A as previously described. V

The invention is not to be limited to ptheexact arrangement of partsshown in the acompanying drawings or, described in this specificationsince various changes in the details of construction'rnay be resorted towithout departing from the spirit of'the invention. For example, theweights 99 employed in connection with the lapping ofthe annularsurfaces on the various articles A are employed herein first because thenature of the article is such that its inherent, mass is insuflicient togive the necessary lapping pressure on the land areas 24. Secondly, theweights afford a' true cylindricalsnrfaceagainst which-the restrainingrollers 102 and 104 maybear so that the articles may turn freely on thesurface of the lap. Obviously, where articles which in themselves arepossessed of sufiicient weight to give'the necessary lapping pressureand wherethe'se articles themselves have cylindrical surfaces positionedabove the plane of the annular surfaces undergoing lapping, the use ofthe weights 99 may be dispensed with. Where the weights 99 are employed,they may be regarded as constituting a portion of the article undergoinglapping and in the following claims where the article is recited ashearing against the rollers 102 or 104, as the case may be, it will beunderstood that the article includes not only the illustrated gear partsbut also the weight which is temporarily associated therewith forlapping purposes.

What I claim is:

1. In an apparatus for lapping an annular surface provided on a shoulderformed on an article concentric with a stem portion projecting .beyondthe shoulder, said article being formed with an exterior cylindricalsurface above said shoulder, in combination, a machine framework, arotatable lap plate mounted on said framework and having anannulargroove providing land portions on opposite sides thereof,saidlapplatebeing adaptedto receive the article'thereon with saidannular surface resting on said land portions and bridging the distancebeyond the same and with said stem portion extending into the groove,and means for restraining said article against revolution about the axisofrotation of the lap plate while permitting independent rotation of thearticle about its own axis, said means comprising anantifriction rollersupported from the machine framework above the plane of the surface ofthe lap plate andpositioned in the normal path of movement of thearticle, said antifriction roller having running engagement with saidcylindrical surface .on the article and being so positioned as to bearagainst the cylindrical surface of the latter so as to hold the. sameagainst circumferential movement on the lap plate andbias the article sothat the stem portion thereof will bear against one side of the .groovein rolling engagement with the latter to induce rotation of the articleon the lap .plate about its own vertical axis, said .a'ntifrictionroller constituting the sole means for restraining said article againstrevolution about the axis of rotation of the lap plate.

2. In an apparatus for lapping an annular surface provided on a soulderformed on an article concentric with a stem portion projecting beyondthe shoulder, said article being formed with an exterior cylindricalsurface above said shoulder, in combination, a machine framework, arotatable lap plate mounted on said framework and having an annulargrooveproviding land portions on opposite sides thereof, said lap platebeing adapted to receive the article thereon with said annular surfaceresting on said land portions and bridging the distance beyond the sameand with said stem portion extending into the groove, means forrestraining said article against revolution about the axis of rotationof the lap plate while permitting independent rotation of the articleabout its .own axis, said means comprising an antifriction rollersupported from the machine framework above the plane of the surface ofthe lap plate and positioned in the normal path of movement of thearticle, said antifriction roller having running engagement with saidcylindrical surface on the article and being 50 positioned as to bearagainst said cylindrical surface of the article so as to hold the sameagainst circumferential movement on the lap plate and bias the articleso that said stem. portion of the latter will bear against one side ofthe groove in rolling engagement with the latter to induce rotation ofthe article on the lap plate about its own verticalaxis, and means foradjusting the position of saidantifriction device radially of the lapplate, said antifriction roller constituting the sole means forrestraining said article against revolution about the axis ofrotationofthe lap plate.

3. in an apparatus for. simultaneously lapping-annular surfaces providedonshoulders formed on a pair of articles haying stem portionsconcentricwith the. shoulders and projectingtherebeyond andhavingexterior cylindrical surfaces above the shoulders, in combination,a machine framework, a rotatable lap plate mounted on said framework andhaving a pair of concentric spaced annular grooves formed therein, eachproviding land portions on opposite sides thereof, said lap plate beingadapted to receive the articles thereon with the annular surface of thearticles each resting on adjacent land portions and with the stemportion extending into the groove between said land portions, and meansfor restraining said articles against revolution about the axis ofrotation of the lap plate while permitting independent rotation of thearticles about their own axes, said means comprising a support carriedby the machine framework, a pair of arms mounted on said support, aroller mounted on each arm and positioned above the plane of the surfaceof the lap plate in the normal path of movement of one of the articles,said rollers each having running engagement with the cylindrical surfaceon one of the articles and being so positioned as to bear against thecylindrical surface of the article so as to hold the same againstcircumferential v movement on the lap plate and bias the article so thatthe stem portion of the article will bear against one side of the groovein which it is mounted in rolling engagement with said side of thegroove to induce rotation of the article on the lap plate about its ownvertical axis, said roller constituting the sole means for restrainingthe article against revolution about the axis of rotation of the lapplate, and means for adjusting the position of said support radially ofthe lap plate.

4. In an apparatus for simultaneously lapping annular surfaces providedon shoulders formed on a pair of articles having stern portionsconcentric with the shoulders and projecting therebeyond and havingexterior cylindrical surfaces above the shoulders, the combination setforth in claim 3 wherein said arms are independently adjustable on saidsupport and means common to said arms for clamping the same in anydesired position of radial and circumferential adjustment relative tothe lap plate.

5. The combination set forth in claim 3 wherein each of said arms isformed with an elongated slot therein, a clamping stud common to saidarms and projecting through the slots formed therein, said stud beingformed. with a clamping head thereon, and means for moving said clampingstud toward and away from said support from a position of release to alocked position wherein the head of the stud serves to clamp said armstogether and against a portion of said support.

6. A work holding fixture designed for use in connection with an annularlap plate having inner and outer concentric circular grooves formedtherein, each adaptedto receive therein the downwardly projecting stemportion of an article having an annular shoulder surrounding the stemportion with the shoulder being supported in lapping relationship on theplate on the rim portions of the groove on the opposite sides of thelatter; said fixture comprising a spindle having a socket formed in thelower end thereof, a rod slidably and turnably disposed within saidsocket, a clamping stud projecting downwardly from the lower end of saidrod and having an enlarged head thereon, a pair of laterally extendingarms each having a slot formed therein carried at the lower end of saidspindle, said arms overlapping each other so that the slots therein arein at least partial register, said stud projecting through said slotswith the head thereof underlying the lowermost arm, there being a slotformed in the side of said spindle exposing a side of said rod, anoperating pin secured to said rod and projecting laterally outwardlythrough said slot, said rod being movable between a low cred positionwithin said socket wherein the head on said stud releases said clampingarms for adjusting purposes to an elevated position wherein said head ofthe stud is drawn tightly against the underneath side of the lowermostarm to clamp the latter against the uppermost arm and in turn to clampthe latter against the lower end of the spindle whereby said arms arelocked in their adjusted positions, said slot being formed with alateral oifset notch designed for reception therein of said operatingpin, the position of said notch with respect to the slot being such thatwhen the operating pin is received within the notch said rod is in itselevated position, and a roller mounted on each arm for free rotationabout a vertical axis, the combined extent of said arms being such thatthey may be adjusted to position said rollers in overlying relation withrespect to said concentric grooves in the lap plate respectively whensaid spindle is positioned above the lap plate in a vertical position.

7. A combined Work holding fixture and wear ring assembly designed foruse in connection with an annular lap plate having inner and outerconcentric circular grooves formed therein, each adapted to receivetherein the downwardly projecting stem portion of an article having anannular shoulder surrounding the stem portion with the shoulder beingsupported in lapping relationship on the plate on the rim portions ofthe groove on oppo site sides of the latter, said articles each having acylindrical side surface; said assembly comprising an annular wear ringpresenting a downwardly facing annular wear surface adapted to bepositioned loosely on the lap plate with said wear surface resting onsaid rim portions, a yoke member extending across said wear ring abovethe latter and secured at its ends to the ring, a spindle extendingcentrally and vertically through said yoke member and on which said wearring is rotatably mounted and on which it is vertically slidable, a pairof arms mounted on said spindle at the lower end thereof and spacedabove the lap plate, said arms being independently adjustable radiallyon said spindle, means common to said arms for clamping the same in anydesired position of radial adjustment, and a roller mounted on each armfor rotation about a vertical axis and adapted to be positioned forrunning engagement with the cylindrical surface on one of said articlesso as to hold the same against circumferential movement on the lap plateand bias the article so that the stem portion thereof will bear againstone side of the groove in which it is mounted whereby said side willinduce rotation of the article.

References Cited in the file of this patent UNITED STATES PATENTS2,048,334 Oliver Sept. 24, 1945 2,565,590 Bullard Aug. 28, 19512,581,106 Indge Jan. 1, 1952 2,597,382 Roshong May 20, 1952 2,627,144Roshong Feb. 3, 1953 FOREIGN PATENTS 345,443 Germany Dec. 10, 1921

